If you can't afford to replace all the cushions--that was our situation--you might consider what we did: our fabric store sold a batting-type product that was kind of like the memory foam things people put on their mattresses. I bought three pieces of that and tucked a piece inside each cushion (they unzipped). Put cushions back on sofa with memory foam side down (so you still sit on the soft cushion side). Worked for us. Hope you find a solution that works for you.